Quick change power tool chuck

ABSTRACT

An improved quick change power tool chuck is provided which is principally used on a wood working router but could also be used in many other power tool applications. The key features of the quick change chuck are the unique way that it secures the cutting bit from unwanted slippage, the large mechanical advantage thereof and the speed in which a cutting bit can be removed and replaced. The chuck can be aligned and attached to the power tool in the same manner that a standard collet is aligned and attached to the router spindle.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of the filing date of ProvisionalPatent Application No. 60/432,638, filed on Dec. 12, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to quick change chucks for powertools and, more particularly, to an improved chuck that providesincreased holding force without sacrificing ease of bit changing.

[0004] 2. Discussion of Related Art

[0005] Although there are a number of existing chucks and like devicesfor retaining cutting bits in power tools and driven spindles, they allhave some disadvantages which detract from their advantages. Forexample, while some chucks hold the cutting bit with enough force thatslippage will not occur, the changing of the bit can be very cumbersomeand time consuming. Others allow an easy changing of bits but do notprovide enough holding torque to prevent slippage from occurring. Thereare a few chucks that allow easy changing of bits and also provide areasonable amount of holding torque. However, at the present time, thereare no chucks currently available which allow an easy change of thecutting bit and which also provide the increase in mechanical advantagenecessary to enable a large enough force to be exerted on the cuttingbit so as to substantially increase the holding torque. A chuck of thistype would allow the power tool user to spin much larger cutting bits athigher speeds while still maintaining a substantially greater safetymargin because of the increased holding force.

[0006] One chuck of particular interest here is that disclosed in U.S.Pat. No. 5,096,212 to Walsh. Although this chuck has advantages, thereare several disadvantages to the chuck. By way of background, it isnoted that routers are required to spin the cutting bit at a relativelyhigh angular speed, typically above 20,000 rpms. Thus, the design of arouter chuck has to be as lightweight and compact as possible forobvious reasons. Accordingly, if the chuck is relatively heavy and bulkyin size as in the case of the chuck of the Walsh patent, unwanted andsometimes severe vibration can occur, resulting in an unsafe operatingcondition. Further, the chuck of the Walsh patent requires two camswhich secure the tool essentially by pinching the tool shank. Since thecams are harder than the typical tool shank, an unwanted indentation inthe tool shank can result if the cams are over-tightened. Anotherdisadvantage of the Walsh chuck is that the manner in which the nut isattached to the body is inadequate. In this regard, although during theshort time a chuck constructed as disclosed in the Walsh patent wasdistributed no failures were reported, the construction could haveeventually led to catastrophic failure. Finally, the construction of thechuck of the Walsh patent employs some unnecessary parts, includes arelatively weak screw, and, in general, has the appearance of beingcumbersome and awkward to use.

[0007] An improvement in the construction of quick change router chucksand the like is disclosed in U.S. Pat. No. 6,332,619 B1 to DeRosa. Thegenesis of this construction was an attempt to overcome all, or as manyas possible, of the shortcomings of the Walsh chuck. The attempt wassuccessful and the construction of the DeRosa chuck not onlyincorporates several improvements but has been manufactured and sold inquantity to the general public. One improvement is the use of only asingle cam instead of two. The single cam was also modified and isallowed to slightly crush under pressure. However, while the cammaintains its holding power, it does not indent the tool shank. The nutis attached by the use of retaining rings which are much stronger andsafer than the previously used pins. Among other advantages, the size ofthe chuck was greatly reduced by the elimination of one cam and a fewunnecessary internal parts, and a stronger screw was incorporated.However, one disadvantage is that some of the holding power provided bythe chuck had to be sacrificed by the use of the softer cam ineliminating the tool shank indentation problem created by the previoususe of a harder cam.

SUMMARY OF THE INVENTION

[0008] An object of the present invention is to provide a chuck havinggreatly increased holding torque, without relying on set screws, flats,keys or any other such elements or configurations that areconventionally used to prevent angular slippage between the cutting bitand the chuck.

[0009] A further object of the present invention is to preserve therelative ease of bit changing and mounting to the motor tool or spindlethat is characteristic of quick change chucks.

[0010] Another object of the present invention is to allow the spinningof much larger cutting bits more safely, by providing much strongerholding of the bit.

[0011] A further object of the present invention is to greatly improvethe holding strength to weight ratio of the chuck in comparison to otherexisting quick change chucks.

[0012] An additional object of the present invention is to eliminate anyinternal parts that can wear out or fail over time but yet are criticalto the operation of the chuck, such as cams, plates, and the like foundin prior art chucks.

[0013] In accordance with one aspect of the invention, there is provideda chuck device for holding a tool having a tool shaft or a connectingcollet, wherein the device comprises: a chuck body including a centrallongitudinally extending bore therein of a predetermined circumferentialshape for receiving the shaft or collet of the tool, and a pivotableportion movable between a rest position wherein the predeterminedcircumferential shape of the bore is maintained and there is noengagement between the pivotable portion and the shaft or collet of atool received in the bore, and an operative position wherein abore-facing surface of said pivotable portion extends inwardly into saidbore so as to engage the shaft or collet of a tool received in saidbore; and a fastener member, received in an aperture in said chuck body,for, in use, causing pivoting of said pivotable portion of said chuckbody to a said operative position thereof so that the bore-facingsurface of said pivotable portion engages the shaft or collet of a toolreceived in said bore.

[0014] Preferably, in the operative position of the pivotable member,the bore-facing surface of the pivotable member engages at leastsubstantially one-half of the outer circumferential surface of the shankor collet.

[0015] In a preferred implementation, the pivoting portion of the chuckdevice is formed integrally with the chuck body. The chuck bodypreferably includes an annular portion including first and secondorthogonal slots therein which divide said annular portion into saidpivotable portion and a fixed portion. The first slot preferably extendsinwardly from an end surface of the annular portion parallel to thelongitudinal axis of the bore. Advantageously, the annular portionincludes a circumferential surface defining the longitudinal thicknessof the annular portion and first and second opposed end surfaces spacedapart by said thickness, the first slot extends into said first endsurface of said annular portion for a distance greater than one half ofsaid thickness and terminates short of said second end surface, and thesecond slot extends into said annular portion orthogonally to said firstslot from said circumferential surface so as to terminate in saidannular portion along a line a portion of which is substantiallycoextensive with the first slot.

[0016] Preferably, the aperture in which the fastener is receivedextends orthogonally to said bore. Advantageously, the aperture includesa threaded section and the fastener element comprises a cap screwincluding a threaded portion for engaging the threaded section of theaperture. Further, a washer is advantageously disposed on the threadedportion of the cap screw.

[0017] In a further important implementation, the chuck body comprises amain body portion, and the pivotable portion comprises a pivot arm whichis formed separately from the main body portion and is pivotably mountedthereon. Advantageously, the arm is of a substantially U-shapedconfiguration having a first, pivoted end and a second, free end anddefining said bore-facing surface between said first and second ends.Preferably, the fastener element, in use, engages the free end of saidarm to clamp said bore-facing surface of the arm against the shank orcollet of a tool received in the chuck bore. Advantageously, the freeend of said arm includes a threaded opening therein, and the fastenerelement comprises a cap screw including a threaded portion adapted to bescrewed into the threaded opening in the free end of the arm.

[0018] Preferably, the chuck device further comprises a cover for thechuck body, the cover comprising a flat end wall and an annular sidewall and including an opening in said end wall adapted to be alignedwith said central bore in the chuck body and an aperture in said sidewall adapted to be aligned with said aperture in the chuck body.Advantageously, the chuck device further comprises an alignment pin, andthe cover and chuck body include respective recesses in which oppositeends of the alignment pin are received so as to provide alignment of thecover and chuck body. Preferably, the side wall of the cover has aninner surface including a circumferential slot therein, and the chuckdevice further includes a locking ring adapted to be received in saidslot so as to lock said cover on the chuck body.

[0019] Preferably, the chuck body further includes a tapered portionthrough which said bore extends, and the chuck device further comprisesa nut adapted to be affixed to the tapered portion. Advantageously, thenut includes a side wall having internal screw threading and including acircumferential slot, the tapered portion of said chuck body includes acircumferential slot in an outer surface thereof, and the chuck devicefurther includes at least one locking ring adapted to be received in theslots in said nut and said tapered portion of said main body so as toprovide locking of said nut on said chuck body.

[0020] According to a related aspect of the invention, there is provideda chuck device for holding a tool having a tool shaft or a connectingcollet, the device comprising: a chuck body including a centrallongitudinally extending bore therein of a predetermined circumferentialshape for receiving the shaft or collet of the tool, and comprising afixed portion and a deformable portion including one end connected to,and formed integrally with, said fixed portion, said deformable portionbeing movable between a rest position wherein the predeterminedcircumferential shape of the bore is maintained and there is noengagement between the deformable portion and the shaft or collet of atool received in the bore, and an operative position wherein abore-facing surface of said deformable portion extends inwardly intosaid bore so as to engage the shaft or collet of a tool received in saidbore; and a fastener member, received in an aperture in said chuck body,for, in use, causing movement of said deformable portion of said chuckbody to a said operative position thereof so that the bore-facingsurface of said deformable portion engages the shaft or collet of a toolreceived in said bore.

[0021] As above, in the operative position of the deformable portion,the bore-facing surface of the deformable portion preferably engages atleast substantially one-half of the outer circumferential surface of theshank or collet.

[0022] Further features and advantages of the present invention will beset forth in, or apparent from, the detailed description of preferredembodiments thereof which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is an exploded perspective view of a preferred embodimentof the chuck assembly of the present invention;

[0024]FIG. 2 is a side elevational view, partially in section, of theassembly of FIG. 1;

[0025] FIGS. 3(a) and 3(b) are an exploded end elevational view and sideelevational view, respectively, of the main body of FIG. 1 showing theslits in the main body that allow the clamping of the tool bit; and

[0026]FIG. 4 is an end elevational view of the main body in accordancewith an alternative embodiment for clamping of the tool bit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027]FIG. 1 shows an exploded perspective view of a preferredembodiment of the chuck device of the invention while FIGS. 2, 3(a) and3(b) show various features of this embodiment. The chuck device iscomposed of nine parts as shown in FIG. 1, viz., a safety cover 300, amain body 301, a pin 310, a washer 311, a cap screw 312, a lock ring314, a nut 315, and two further lock rings 316 and 317.

[0028] In accordance with a key feature of the invention, the main body301 is adapted to be mechanically deformed by the incorporation thereofof two slots 323 and 324 that extend perpendicular to each other. Theseslots are perhaps best seen in FIG. 3(b) and, as shown, divide anannular end portion of main body 301 into a fixed part or side 301 a anda movable part or side 301 b. As illustrated in FIG. 3(a), slot 323extends inwardly from the circumferentially extending side surface ofmain body 301 so as to terminate in the main body 301 along a line(indicated by the dashed line 323) a portion of which is coextensivewith orthogonal slot 324. Slots 323 and 324 thus create a movable orpivotable portion 301 b of main body 301 which is capable of pivotablemovement or flexing about the base portion thereof if sufficient forceis applied thereto. Thus, when the cap screw 312 is tightened againstthe fixed side 301 a of the cam body 301, the opposite side 301 b of thebody 301 defined by the slots 323 and 324 can flex and translate. Mainbody 301 includes a central aperture 303, and the inward translation ofpivotable part 301 b causes a slight inward distortion of the centralaperture 303, as is indicated in dashed lines in FIG. 3(a). This enablesa large clamping force to be applied to a tool shank or collet (notshown) which has been inserted into the main aperture 303 of the device.

[0029] Considering this clamping operation in more detail, the main body301 also includes a further aperture 305, which extends perpendicular tocentral aperture 303. As indicated above, aperture 303 allows placementof the tool shank (not shown) into the slightly deformable main body301, whereas aperture 305 allows insertion therein of the cap screw 312,through the washer 311. Cap screw 312 includes a threaded portion 312 aadapted to engage to threads 306 of aperture 304. When the threadedportion 312 a of cap screw 312 is tightened onto threads 306, cap screw312 pulls the deformable part 301 b of the body 301 against the toolshank or collet (not shown) thereby exerting a large forcecircumferentially on the tool shank or collet. A large mechanicaladvantage is obtained by applying the force tangentially to thedeformable body 301 with cap screw 312. The arrangement of deformablepart 301 b is such that the inner, bore-facing surface of deformableportion 301 b engages substantially one-half of the outer surface of theshank or collet and the main body 301 forms almost a complete “noose”around the tool shank so that the tool is held almost completely aroundthe circumference of the tool shank. It will be understood that althoughin this embodiment the bore-facing surface of deformable portion 301 bengages substantially one-half of the outer surface of the shank orcollet, a lesser portion of the shank or collect can be engaged andstill provide the noose effect.

[0030] It will be appreciated from the foregoing that disengagement ofthe tool shank is readily achieved. In this regard, when cap screw 312is loosened, the deformable part 301 b of body 301 springs back to itsrelaxed or rest position, thereby freeing the tool shank to be removed.

[0031] As best seen in FIG. 2, the pin 310 is used to align the safetycover 300 which covers the main deformable body 301 with the body 301itself and, to this end, opposite ends of pin 310 are received inrespective apertures in cover 300 and main body 301. Cover 300 alsocontains a central aperture 302 which allows the tool shank to beinserted into aperture 303. Pin 310 also allows aperture 305 and afurther aperture 320 (see FIG. 2) provided in the side wall of cover 300to be aligned so that the cap screw 312 and the washer 311 can beinserted into aperture 305 and engaged with threads 306.

[0032] After the safety cover 300 has been placed in position over thedeformable main body 301, the locking ring or lock ring 314 is insertedinto the bottom of safety cover 300 and into a groove 325 (see FIG. 2)which is formed in the inner circumference of cover 300 so that ring 314and groove 325 function as a permanent retention device.

[0033] The alignment of the main tool aperture 303 with respect to thedriven tool spindle (not shown) is accomplished in the usual, standardmanner by the use of a taper section 318 formed on the body 301. Theconstructional details of the tapered section 318 will change accordingto the requirements of the particular geometrical configuration of thedriven tool spindle. For example, parameters such as the taper angle,diameter, and length will be made to match the configuration of thedriven tool spindle.

[0034] Turning to nut 315, and the manner of connection thereof, to mainbody 301, the aforementioned locking rings or lock rings 316 and 317 areinserted into the nut 315. More particularly, the lock rings 316 and 317are placed into an internal retaining groove 322 located inside of thenut 315. The tapered section or portion 318 of the main body 301 ispushed into a central aperture 321 in nut 315 as shown in FIG. 2, thusallowing the locking rings 316 and 317 to expand and snap into acircumferential groove 319 in tapered portion 318, thereby permanentlyattaching the nut 315 to the main body 301.

[0035] After the placement of the nut 315 is completed, the locking ring314 becomes totally inaccessible and disassembly of the chuck becomesimpossible unless the chuck is destroyed or otherwise renderedinoperable. This is a safety feature that eliminates unwanted tamperingwith the chuck device.

[0036] Finally, the chuck device is inserted into the driven toolspindle (not shown) and retained thereon by the use of threads 304located on the inside circumferential surface of the nut 315. The nut315 is then tightened onto the driven tool spindle thereby pulling thetapered section 318 of the main body 301 against the matching spindletaper, thereby securing the chuck device to the spindle. After the chuckdevice has been installed onto the router or other spindle, the chuckdevice is ready to accept cutting tools and is otherwise ready for use.

[0037] Referring to FIG. 4, an alternative embodiment of the inventionis shown. This embodiment is similar to that of FIG. 1 and thedescription here will basically focus on the differences between thisembodiment and that of FIG. 1. In FIG. 4, a main body 401 includes aconventional central bore 402, and also includes a milled cavity 403which receives a rotating or pivoting arm 404.

[0038] Arm 404 pivots around a pin 405 secured to main body 401 withincavity 403. Arm 404 is of a generally U-shaped construction, asillustrated, so that the inner curved surface thereof can engage thetool shank (not shown) received in bore 402. The free end of arm 404 isengaged by a threaded portion or section 406 a of a cap screw 406 whichis received, with a suitable clearance, in a bore 407 in main body 401.Cap screw 406 is thus used to control tightening and loosening of theengagement between the inner surface of arm 404 and the tool shank orcollet (not shown).

[0039] It is noted that in both embodiments described above the capscrew (312 or 406) screws into the movable or pivotable portion from thefixed portion but it will be understood that the cap screw (or othertightening element) can also screw into the fixed portion from thepivotable portion.

[0040] Although the invention has been described above in relation topreferred embodiments thereof, it will be understood by those skilled inthe art that variations and modifications can be effected in thesepreferred embodiments without departing from the scope and spirit of theinvention.

What is claimed:
 1. A chuck device for holding a tool having a toolshaft or a connecting collet, said device comprising: a chuck bodyincluding a central longitudinally extending bore therein of apredetermined circumferential shape for receiving the shaft or collet ofthe tool, and a pivotable portion movable between a rest positionwherein the predetermined circumferential shape of the bore ismaintained and there is no engagement between the pivotable portion andthe shaft or collet of a tool received in the bore, and an operativeposition wherein a bore-facing surface of said pivotable portion extendsinwardly into said bore so as to engage the shaft or collet of a toolreceived in said bore; and a fastener member, received in an aperture insaid chuck body, for, in use, causing pivoting of said pivotable portionof said chuck body to a said operative position thereof so that thebore-facing surface of said pivotable portion engages the shaft orcollet of a tool received in said bore.
 2. A chuck device according toclaim 1 wherein the shaft or collet of the tool has an outercircumference and wherein, in the operative position of said pivotablemember, the bore-facing surface of the pivotable member engages at leastsubstantially one-half of the outer circumferential surface of the shankor collet.
 3. A chuck device according to claim 1 wherein said pivotingportion is formed integrally with the chuck body.
 4. A chuck deviceaccording to claim 3 wherein said chuck body includes an annular portionincluding first and second orthogonal slots therein which divide saidannular portion into said pivotable portion and a fixed portion.
 5. Achuck device according to claim 4 wherein said first slot extendsinwardly from an end surface of the annular portion parallel to thelongitudinal axis of the bore.
 6. A chuck device according to claim 4wherein said annular portion includes a circumferential surface definingthe longitudinal thickness of the annular portion and first and secondopposed end surfaces spaced apart by said thickness, wherein said firstslot extends into said first end surface of said annular portion for adistance greater than one half of said thickness and terminates short ofsaid second end surface, and wherein said second slot extends into saidannular portion orthogonally to said first slot from saidcircumferential surface so as to terminate in said annular portion alonga line a portion of which is substantially coextensive with said firstslot.
 7. A chuck device according to claim 1 wherein said aperture inwhich said fastener is received extends orthogonally to said bore.
 8. Achuck device according to claim 7 wherein said aperture includes athreaded section and wherein said fastener element comprises a cap screwincluding a threaded portion for engaging the threaded section of saidaperture.
 9. A chuck device according to claim 8 further comprising awasher disposed on said threaded portion of said cap screw.
 10. A chuckdevice according to claim 1 wherein said chuck body comprises a mainbody portion and said pivotable portion comprises a pivot arm formedseparately from said main portion and pivotably mounted thereon.
 11. Achuck device according to claim 10 wherein said arm is of asubstantially U-shaped configuration having a first, pivoted end and asecond, free end and defining said bore-facing surface between saidfirst and second ends.
 12. A chuck device according to claim 11 whereinsaid fastener element, in use, engages the free end of said arm to clampsaid bore-facing surface of said arm against the shank or collet of atool received in said bore.
 13. A chuck device according to claim 12wherein said free end of said arm includes a threaded opening therein,and wherein said fastener element comprises a cap screw including athreaded portion adapted to be screwed into said threaded opening.
 14. Achuck device according to claim 1 further comprising a cover for saidchuck body, said cover comprising a flat end wall and an annular sidewall and including an opening in said end wall adapted to be alignedwith said central bore in said chuck body and an aperture in said sidewall adapted to be aligned with said aperture in said chuck body.
 15. Achuck device according to claim 14 wherein said device further comprisesan alignment pin, and wherein said cover and said chuck body includerespective recesses in which opposite ends of said alignment pin arereceived so as to provide alignment of said cover and said chuck body.16. A chuck device according to claim 14 wherein said side wall of saidcover has an inner surface including a circumferential slot therein, andwherein said device includes a locking ring adapted to be received insaid slot so as to lock said cover on said chuck body.
 17. A chuckdevice according to claim 1 wherein said chuck body further includes atapered portion through which said bore extends, and wherein said chuckdevice further comprises a nut adapted to be affixed to said taperedportion.
 18. A chuck device according to claim 17 wherein said nutincludes a side wall having internal screw threading and including acircumferential slot, wherein said tapered portion of said chuck bodyincludes a circumferential slot in an outer surface thereof, and whereinsaid chuck device further includes at least one locking ring adapted tobe received in the slots in said nut and said tapered portion of saidchuck body so as to provide locking of said nut on said chuck body. 19.A chuck device for holding a tool having a tool shaft or a connectingcollet, said device comprising: a chuck body including a centrallongitudinally extending bore therein of a predetermined circumferentialshape for receiving the shaft or collet of the tool, and comprising afixed portion and a deformable portion including one end connected to,and formed integrally with, said fixed portion, said deformable portionbeing movable between a rest position wherein the predeterminedcircumferential shape of the bore is maintained and there is noengagement between the deformable portion and the shaft or collet of atool received in the bore, and an operative position wherein abore-facing surface of said deformable portion extends inwardly intosaid bore so as to engage the shaft or collet of a tool received in saidbore; and a fastener member, received in an aperture in said chuck body,for, in use, causing movement of said deformable portion of said chuckbody to a said operative position thereof so that the bore-facingsurface of said deformable portion engages the shaft or collet of a toolreceived in said bore.
 20. A chuck device according to claim 19 whereinthe shaft or collet of the tool has an outer circumference and wherein,in the operative position of said deformable portion, the bore-facingsurface of the deformable portion engages at least substantiallyone-half of the outer circumferential surface of the shank or collet.